[Docker image] Fix package installation at runtime with packages/store mounted as a volume

docker run -it --rm --name nuxeo -p 8080:8080 \
-e NUXEO_CLID="$(cat /path/to/instance.clid)" \
-v vol-packages-store-11:/opt/nuxeo/server/packages/store \
-e NUXEO_PACKAGES=nuxeo-web-ui \
nuxeo/nuxeo:latest

ENTRYPOINT: Install Nuxeo packages: nuxeo-web-ui
Nuxeo home:          /opt/nuxeo/server
Nuxeo configuration: /etc/nuxeo/nuxeo.conf
Include template: /opt/nuxeo/server/templates/common-base
Include template: /opt/nuxeo/server/templates/common
Include template: /opt/nuxeo/server/templates/default

Dependency resolution:
  Installation order (1):        nuxeo-web-ui-3.1.0-SNAPSHOT
  Packages to download (1):      nuxeo-web-ui:3.1.0-SNAPSHOT

Downloading [nuxeo-web-ui-3.1.0-SNAPSHOT]...
org.nuxeo.connect.update.PackageException: Failed to unzip package: nuxeo-web-ui-3.1.0-SNAPSHOT
Downloading [nuxeo-web-ui-3.1.0-SNAPSHOT]...
org.nuxeo.connect.update.PackageException: Failed to unzip package: nuxeo-web-ui-3.1.0-SNAPSHOT
Failed to install package: nuxeo-web-ui-3.1.0-SNAPSHOT (Package not found: nuxeo-web-ui-3.1.0-SNAPSHOT)

Failed commands:
* install (nuxeo-web-ui-3.1.0-SNAPSHOT)
	Package not found: nuxeo-web-ui-3.1.0-SNAPSHOT
* add (nuxeo-web-ui-3.1.0-SNAPSHOT)
	Could not find downloaded package in cache nuxeo-web-ui-3.1.0-SNAPSHOT